I'm a homebrewer who has to fit brewing in with family life so I'm always looking to streamline my process. I primarily use rehydrated safale yeast and I'm wondering if it's ok for the yeast to sit in the water overnight so I can pitch first thing in the morning before I go to work?

I figure I can save a lot of time by cooling the wort to around 100-110 and then let it come down to pitching rates overnight. It doesn't take long to get the wort to 100 but it takes a long time to get it to 65.

Is this safe? If so, should the yeasties sit at room temp overnight or in the refrigerator?

If you're going to let it sit out overnight why not feed it some malt so it can come alive and be ready to feast?

Leaving wort to sit out overnight is not a good practice because it is most susceptible to bacteria at certain temps. The trick with cooling is you want to lower the temp past that range and get the brew ready ft start fermenting. How much (volume) do you boil?

I boil 1.5 gal batches and top off with filtered tap water that I place in 1 gal jugs and place in the freezer for 4-5 hours prior to brewing. As soon as I top it off it is in the 60-70F range and ready for the yeast. Since the water is not boiled it already contains the oxygen needed for aeration so vigorous stirring is not necessary.

Something you may want to consider if you are looking to streamline your process.

Yep, any time it spends below a certain temp but before pitching is just more time for a possible infection to take hold. IMO, it's unlikely that you would have very much issue leaving it for just a night, but it's still a risk I would prefer not to take unless I had to.

If you do go that route, I would not rehydrate the yeast the night before... rehydrating doesn't take very long, you could start it when you get up and then pitch before you leave.

For dried yeast, you don't have to rehydrate. There is plenty discussion on here about that. But rehydrating the yeast is meant to be done before they go to work on the wort. So if you are trying to cut this out so that you can pitch before work, I would just skip rehydrating altogether. Rehydrating doens't take that long anyway.

As for letting the wort cool overnight. I wouldn't recommend this. As mentioned, the wort will be susceptible to bacteria as the temp drops.

Just do this: the day before brewing, sanitize some Rubbermaid or Tupperware-style plastic containers with tight-fitting lids, and boil up some water. Add hot water to the plastic containers, put the lid on, let them cool off a bit and then stick them in the freezer.

The next day, add the blocks of ice to your wort as it cools. Not only are you going to get one hell of a cold break, but you'll also end up with pitchable wort very quickly. Much lower risk of infection that way.

Well, all good points. The actual question was about rehydrating dry yeast in advance. The answer to that is no. You should not rehydrate any more than 10-15 minutes before pitching. Any longer is detrimental to the yeast.